How to i pass variable value to input text value? - function

Question

I would like to compare user input with predefined value on same jsp page. If the input value is same as expected, then i allow user go ahead to submit the request form. But i don't know how set the predefined value for checking. Thanks.
<tr><td>Application</td></tr>
<%
String strDBCode = "123456789";
out.println("<tr><td><b>Please input your pass code here:</b></td></tr>");
out.println("<tr><td><input type='text' name='strPassCode' value=''></td></tr>");
out.println("<tr><td><input type='hidden' name=strDBPassCode size='15' maxlength='15' value=strDBCode id='b'></td></tr>");
out.println("<tr><td><input type='button' name='chkPassCode' value=' Check ' onClick='return chkPCode()'></td></tr>");
%>
<script type="text/javascript">
function chkPCode()
{
var a = document.getElementById("a");
var b = document.getElementById("b");
var valid = true;
if (a.value != b.value) {
alert("Not Match!");
valid = false;
}
else {
alert("Match");
valid = true;
}
return valid;
}
</script>
I expect b value should be "123456789", but b always equal to "strDBPassCode". I have try set
out.println(" id='b'>");
It return error. Since the input already inside <% %>.
Apart from that, how to disable the input text box if valid return is true?
Any idea? thanks.

Answer 1

This is because you are not referring to the variable you declared.
out.println("<tr><td><input type='hidden' name=strDBPassCode size='15' maxlength='15' value="+strDBCode+" id='b'></td></tr>");
__________↑
Similar way, you can update the name attribute in above code.
Do not write scriptlets in JSP, because scriptlets shouldn't be used in JSPs for more than a decade. Learn the JSP EL, the JSTL, and use servlet for the Java code.
See How to avoid Java Code in JSP-Files?

Answer 2

<script type="text/javascript">
function chkPCode()
{
var a = document.getElementById("a");
var b = document.getElementById("b");
var valid = true;
if (a.indexOf(b) == -1) {
alert("Not similar!");
valid = false;
}
else {
alert("Input value exist!");
valid = true;
}
return valid;
}
</script>